问socket.io让我感到困惑，我如何通过已有的同一端口建立连接？

EN

const express = require('express');
const path = require('path');
const hbs = require('hbs');
const socket = require('socket.io');

const methodOverride = require('method-override');
const flash = require('connect-flash');
const session = require('express-session');
const bodyParser = require('body-parser');
const passport = require('passport');
const mongoose = require('mongoose');

const config = require('./config/config');

const app = express();

// Load routes
const main = require('./routes/main');
const users = require('./routes/users');

// Connect to mongoose
mongoose.connect(config.db.host, {
  // useMongoClient: true
}).then(() => console.log('MongoDB Connected...'))
  .catch((err) => console.log(err));


// Routes

// Use routes
app.use('/', main);
app.use('/users', users);

const port = process.env.PORT || 3000;

// Socket.io 

var io = socket(port);
function newConnection(socket){
  console.log(socket);
}

io.sockets.on('connection', newConnection);


app.listen(port, () => {
  console.log(`Server started on port ${port}`);
});